Method and apparatus for introducing mercury into a discharge device by means of a capillary tube and a by-pass connection



2,433,177 DISCHARGE 1947- A A. w. WAINIO METHOD AND APPARATUS FOB. IN'I'RODUCINC?- MERCURY INTO A DEVICE BY MEANS OF A CAPILLARY TUBE AND A BY-PASS CONNECTION Filed Feb. 10. 1944 O INVENTOR 4. 14 AV/V/fl BY 91mm ATTORNEY Mzvetwer 50285 a;- C/iPrLLflzY.

Patented Dec. 23, 1947 METHOD AND APPARATUS FOR INTRODUC- ING MERCURY INTO A DISCHARGE DE- VICE BY MEANS OF A CAPILLARY TUBE AND A BY-PASS CONNECTION Albert W. Wainio, Bloomfield, N. 1., minor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application February 10, 1944, Serial No. 521,906

5Claims. l

The present invention relates to discharge devices and more particularly to the introduction of mercury or other gaseous vapor into the container of such discharge device as, for example. discharge lamps and gaseous electronic devices.

In many discharge devices now commercially employed it is necessary that there be introduced therein a precise quantity of a vaporizable substance such as mercury, as any material deviation from the preselected precise quantity results in erratic performance of the device, or an alteration in its characteristics, such as the starting and operating voltage and the like. Because of this requirement many structures and methods.

have been employed in the past in an effort to introduce the desired quantity of mercury therein. These, however, have proven very unsatisfactory since they involve additional structure built into the lamp to hold the mercury such as what is referred to as a bomb" or the like. Moreover, an additional manufacturing step is required to release or explode the bomb" allowing the mercury to enter the container thus increasing manufacturing costs.

It is accordingly the primary object of the present invention to provide a means for introducing a precise quantity of vaporizable material into the container of a discharge device during the initial stages of its fabrication without the necessity of a separate step in the manufacture thereof.

Another object of the present invention is the provision of a means for introducing a precise quantity of mercury into the container of a discharge device simultaneously with the introduction of the starting gas.

A further object of the present invention is the provision of means for introducing a precise quantity of mercury into the container of a discharge device wherein the pressure exerted by the admission of the customary starting gas is employed to control the introduction of the preselected accurate quantity of the mercury.

Further objects of the present invention will become obvious to those skilled in the art by reference to the accompanyin drawing wherein:

Fig. 1 is an elevational view of the apparatus for the introduction of a precise quantity of mercury into the container of a discharge device in accordance with the present invention, and

Fig. 2 is a graphic illustration showing the relationship between a part of the structure and the quantity of mercury available at a given moment.

Referring now to the drawing in detail a dischange device, such for example as a fluorescent lamp 5, is shown in Fig. 1 during the exhausting and filling position of its fabrication. As shown, the customary exhaust stem 6 of the lamp is connected to an exhaust manifold 'I by means of a coupling 8. The exhaust manifold I is adapted to be coupled directly to an exhaust pump (indicated by the legend "To pump) by operation of a valve 9. Two branches connect with the manifold I, one such branch-being coupled, as desired, to a source of the customary starting gas, such as argon, neon or the like (indicated by the legend To fill gas"), by operation of a valve I0. The second branch l2 extends to a reservoir I3 containing a quantity of mercury l4 which gravitates into the angularly positioned exhaust manifold I upon opening of a control valve [5 similar to the valves 9 and 10.

It will be noted that the angularly disposed exhaust manifold I is provided, immediately above the coupling 8, with a vertical portion constituting what may be termed a chamber IS with a capillary tube l'I extending therein and in effect being an outlet for the manifold I. A bypassing conduit l8 connects the chamber IS with the angularly disposed exhaust manifold "I at a point a substantial distance along its length de-' pending upon the angulation thereof thus shunting the capillary tube II. This by-passing conduit I9 is also provided with a valve l9 serving the purpose when opened of establishing communication between the manifold I and the chamber 16 and as a restriction in the-passageway as hereinafter described more in detail.

In the operation of-the apparatus the valve I5 is first operated allowing a quantity of the mercury H to gravitate from the reservoir l3 into the angularly disposed exhaust manifold 1 where it is stopped by the capillary tube I1 and thus rises in the exhaust manifold I to a desired height of from approximately one-half to one inch or more depending upon the degree of angulation of exhaust manifold I and the quantity of mercury it is desired to retain therein. In no event, however, must it be permitted to rise so high as to close communication between the bypass conduit I8 and the exhaust manifold I.

The mercury having gravitated to the lower end of the manifold I, the valves 9 and I9 are opened thus establishing communication from the container 5 directly with the vacuum pump through valve 9, chamber [6, by-pass conduit l8 and exhaust manifold I. After the desired degree of evacuation is attained valves 9 and I9 are then closed. Valve l9, which may he graduated in terms of drops of predetermined grams, is then opened to provide a preselected constriction in by-pass conduit II. This valve being accordingv iy opened the desired amount, the valve II is next opened allowing filling gas at the pressure of its source. to enter into manifold l.

The pressure exerted by the admission of the filling gas on the mercury ll within the manifold l forces a drop of mercury through the capillary tube i'l where it gravitates into container 5. The fiow of mercury through the capillary tub'e ll occurs for only a moment until the pressure of the gas exerted on the top of the mercury within the exhaust manifold I, and that exerted on the capillary tube I! from the chamber Ii and hence on the bottom of the mercury column, equalizes through the by-pass conduit l8 and constriction provided by the valve is. The size of the constriction formed by the valve I! thus determies the quantity of mercury in number of drops of preselected weight flowing out of the capillary tube II, which is thus introduced into the container not only simultaneously with the introduction of the filling gas. but actually under the control thereof.

The accuracy with which the amount of mercury is controlled can be appreciated by reference to Fig. 2. In this figure the abscissa represents the bore of the capillary tube in mils (thousandths of an inch) and the ordinate inches of mercury column. The curve A showsthe different heights of mercury column which different bore capillaries will support. The

height of the mercury represented by the ordinate in Fig. 2 in a static column without vibration or some action to start a drop flowing through a capillary outlet. I have found that with a vertical column of mercury any b'ore capillary over 8 mils will run empty once flow is started by vibration or other means to overcome the surface tension. Limiting the capillary bore to less than 8 mils will operate satisfactory to drop the mercury but the weight thereof is limited to 30 milligrams or less. By placing the exhaust manifold I at about a 45 angle or less, a head of mercury varying from approximately one-half inch high to an inch or more depending upon the angle, can be supported and withstand vibration with a capillary bore of 16 mils as shown in Fig. 2 which gives a drop size of 60 milligrams.

It is known that for the same liquid the weights formedwith different bore capillaries are proportional to the diameter of the orifice. Based on this principle I have empirically determined from a curve, wherein the ordinate represented the weight of the mercury drop in milligrams and the abscissa capillary bore in mils, thatsuch curve had an average slope indicating the average proportion between the weight of the mercury drop and the bore of the capillary to be a factor of "3.8. Accordingly. y multiplying the capillary bore in mils by this factor of 3.8 gives the approximate weight of each drop of mercury in milligrams.

A practical range is from to 60 milligrams at a 45 angle for the capillary which means a bore size for the latter from about 3.8 mils to 16.0 mils. A standard fluorescent lamp, such as shown in Fig. 1 during'its fabrication, requires about 40 milligrams which necessitates a capillary bore of 10.5 mils and would support a head of mercury about one-inch in height at the 45 angle of exhaust manifold 1. If it is desired the capillary may be made one-half the-size, namely,

a 4 5.25 mils and the valve ll adjusted to cause the pressure of the filling gas to drop two drops of 20 milligrams each before pressure equalization occurs as previously mentioned.

From the foregoing it will become obvious to those skilled in the art that a means is herein shown and described for introducing a precise quantity of mercury or other vaporizable material into the container of a discharge device. Moreover, such vaporizable material is not only introduced simultaneously with the filling gas but under the control thereof. It is also obvious that, although the introduction of the vaporizable material has been herein described as introduced under the control of the filling gas,

for the purpose of eliminating a step in the manufacture of the device and thus decreasing the manufacturing cost thereof, it can be separately introduced, if desired, simply by maintaining the mercury column in a static condition within a capillary tube and vibrating the latter or applying some other force thereto, thus causing flow of the vaporizable material through the tube a drop at a time.

' Although one specific embodiment of the present invention has been shown and described, it is to be understood that further modification thereof may be made without departing from the spirit and scope of the appended claims.

I claim:

1. The method of introducing a quantity of vaporizable material into a container for a discharge device which consists in retaining the material within a capillary tube having a predetermined bore and disposed in'the manifold of an exhaust system communicating with the device. evacuating the device of gases, by-passing the withdrawn gases around the capillary tube and the material therein, and applying a force to the material within the capillary tube to cause a preselected portion of the material within the capillary tube to flow therethrough into the container.

2. The method of introducing a quantity of vaporizable material into a container for a discharge device which consists in retaining the ma terial within a capillary tube having a predetermined bore and disposed in the manifold of an quantity of vaporizable material into the contamer for a discharge device comprising an exhaust system provided with a manifold for evacuating the container, a capillary tube having a preselected bore and disposed in said manifold. a quantity of vaporizable material disposed in said capillary tube, a by-pass connection around said capillary tube and the material therein, and means for applying aforce to the material in said capillary tube sufficient to overcome the surface tension of said material and cause a precise portion thereof to flow through the capillary tube into the container for said device.

4. An apparatus for introducing a preselected quantity of vaporizable material into the container for a discharge device comprising an exhaust system provided with a manifold for evacuating the container, a capillary tube having a preselected bore and disposed in said manifold, a quantityof vaporizable material disposed in said capillary tube, said exhaust system including a by-pass connection around said capillary tube and the material therein, and connections from said manifold to a source of filling gas for introducing the latter into the container of said device with the pressure thereof causing the flow of a preselected amount from said quantity of material through the capillary tube into the container for said device, and said by-pass connection enabling the pressure exerted by the filling gas on the opposite side of the capillary tube to equalize with the pressureof the filling gas exerted on the material within said capillary tube. V

5. An apparatus for introducing a preselected quantity of vaporizable material into the container for a discharge device comprising an exhaust system provided with a manifold for evacuating the container, a capillary tube having a preselected bore and disposed in said manifold, a quantity of vaporizable material disposed in said capillary tube, said exhaust system including a by-pass connection around said capillary tube and the material therein, connections from said manifold to a source of filling gas for introducing the latter into the container of said device with the pressure thereof causing the flow of a preselected amount from said quantity of material through the capillary tube into the container for said device, and said by-pass connection enabling the pressure exerted by the filling gas on the opposite side of the capillary tube to equalize with the pressure of the filling gas exerted on the material within said capillary tube, and an adjustable constriction in said by-pass connection for regulating the flow of filling gas therethrough to control the quantity of the preselected amount of vaporizable material flowing through said capillary tube when subjected to the pressure of the filling gas.

ALBERT W. WAINIO.

REFERENCES CITED UNITED STATES PATENTS 25 Number Name Date 158,564 Barnes Jan. 12, 1875 2,326,296 Harrison et al. Aug. 10, 1943 

